Refrigerating apparatus



Sept. 21, 1937.

Filed Dec. 24, 1934 H. B. HULL REFRIGERAT ING APPARATUS.

3 Sheets-Sheet 2 Sept. 21, 1937. HULL 2,093,725

REFRIGERATING APPARATUS Filed Dec. 24,- 1934 3 SheetsSheet 3 I '52s 159V4 I 1 INV MTOR.

W Z ATTORI; Y5

Patented Sept. 21, 1193? warren stares atoms 'E' @FFHQE 2,093,725 Vnarmeam'rmc APPARATUS Harry B. Hull, Dayton, Ohio, assignorto GeneralMotors Corporation, Dayton, Ohio, a corporation of Delaware inventionwill beapparent from the following.

description, reference being had to the accompanying drawings, wherein apreferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a view, somewhat diagrammatic, and partly in cross-section ofan apparatus embodying features of my invention;

Fig. 2 is a view somewhat similar to Fig. 1 but.

showing a slightly modified form;

Fig. 3 is a view, showing a modified form of control for a portion ofthe apparatus shown in Fig. 2;

Fig. 4 is a view somewhat similar to Fig. l and showing a furthermodification;

Fig. 5 is a view, somewhat similar to Fig. 1, but showing. a furthermodification;

Fig. 6 is a view in perspective of a portion of v the apparatus shown inFig. 5; and

Fig. 7 shows a switchresponsive to relative humidity conditions.

In practicing this invention, instrumentalities are provided fortransferring heat from air to be conditioned to a fluid. Thereafter theair is cooled by some independent instrumentality.

' The heat which has been transferred to the fluid the heat transferredto the fluid may be introduced into conditioned air in order to avoid anundue lowering of the dry bulb temperature, or to increase thedehydrating power of the apparatus.

To this end, the air conditioning apparatus or method includes means forestablishing the flow of a stream of ain'which conveniently may take theform of a fan It! driven by a motor I l, the air circulating through acasing 12 and through the outlet l3 into the'space A for wh'ch the airis Application December, 24, 1934, Serial No. 758,884

21 Claims.

to be conditioned. Means for removing or transferring heat from the airto a circulating fluid or secondary refrigerant may take the form of asecondary refrigerant evaporator l4 placed in thermal exchange with theair stream. Means for cooling the air independently of the evaporator 14may take the form of a primary refrigerant evaporator IS in thermalexchange with the air stream. Means for introducing heat from thesecondary refrigerant into conditioned air may take the form of asecondary refrigerant condenser I6, which may be placed anywhere inthermal exchange relationshipwith cohditioned air. Conveniently it maybe placed in the path of the air stream which is being conditioned.

A refrigerant liquefying unit I1 may be placed in primary refrigerantflow relationship with the evaporator l5 to furnish the necessaryrefrigeration. This refrigerant liquefying unit I! conveniently may takethe form of a compressor i8,

a primary refrigerant condenser l9, and liquid receiver 20. The unit I!may be driven by an electric motor 2|. flows through the line 22 andthrough the automatic expansion valve 23 to .the evaporator IS. Theevaporated primary refrigerant returns through the evaporatedrefrigerant line 24, to the compressor l8.

The expansion valve 23 may be of the type which automatically introducesliquid refrigerant into the evaporator l5 when the pressure in theevaporator is reduced below a predetermined limit. This valve may alsobe provided with a thermostatic bulb 25 placed in thermal exchange withthe outlet of the evaporator and which automatically throttles the valve23 when the refrigerating effect becomes sufficiently efiective on thebulb'25. The calibration of the valve 23 preferably is such that thetemperatureof the air cooling surface of the evaporator I5 is maintainedabove the freezing point of water; but it is to be understood that, ifdesired, the evaporator may be operated at any temperature below thefreezing point of water and may be periodically defrosted eitherduringeach cycle of the unit H, or by a special defrosting cycle.

Means for controlling the flow of heat between the air and thecirculating fluid or secondary refrigerant may be provided. Such meansmay be- .made responsive to any air conditions.

Preferably such means are made responsive to the relative humidityconditions of the air in the enclosu.e A. To this end. a psychrometer orhumidis'at 2% may control the flow of secondary refrigerant from theevaporator l4 to the condenser Liquid primary refrigerant I6.Conveniently this may be accomplished by mounting the condenser I6swingably on the fulcrum 21 so that the same may be swung into arefrigerant trapping condition by the action of the psychrometer 26.Thus a lever 28, which is attached to the condenser I6, is rocked aboutthe fulcrum 29 by the psychrometer 26. When the condenser is in theupper position shown in full lines, the secondary refrigerant flows fromthe evaporator I4 in gaseous form up through the line 36. ,The secondaryrefrigerant is condensed in the condenser I6 and returns to theevaporator I4 by flowing down through the line 30. When the condenser I6is in the lower position, shown in dotted lines, it traps the liquidrefrigerant and stops or reduces the interchange of heat between suchrefrigerant and the air.

The psychrometer 26 may be of any suitable construction. For example, itmay include a dry bulb 3|, and a wet bulb 32 in opposed relationship.When the relative humidity is high, the pressures within the bulbs3I-and 32 tend to be nearly equal and thus the rod 33 moves upwardlythereby moving the condenser upwardly and causing heat exchange betweenthe secondary refrigerant and the air to take place. When the relativehumidity is low, a large variation exists between the dry and wet bulbtemperatures, and therefore the pressure within the dry bulb 3| tends toexceed greatly that of the wet bulb 32. Therefore the rod 33 movesdownwardly, lowering the condenser I6 and trapping the secondaryrefrigerant in the condenser thus stopping the flow of secondaryrefrigerant and its action upon the air. A spring 34, connected to thelever 28 and bracket 35, may be adjusted by the screw and knob 36, sothat the relative humidity to which the psychrometer is responsive maybe varied or selected to suit individual requirements.

Means may be provided for controlling the thermal exchange between theair and the primary refrigerant. Such means may be made responsive toair conditions and preferably are made responsive to comfort conditionsin the space for which the air is being conditioned. Thus an automaticswitch 40 may control the starting and stopping of the motor 2 I. Theautomatic switch 40 may be of the type which is responsive to comfortconditions, or effective temperature conditions in the space.Conveniently it may take the form of a bi-metallic thermostat 4| havingelectric contacts Ma. The thermostat 4| is mounted upon the swingingplatform 42 which is carried by base 42a. Platform 42 is actuated by anymeans 43, such as a piece of wood, which is responsive to relativehumidity conditions in the room. The platform 42 may swing about thepivot 44 and is actuated by the wood block 43 through the medium of thelever .45. The means 43 modulates the action of the thermostat 4| inresponse to relative humidity conditions and thus starts and stops theunit I! in response to effective temperature within the space to beconditioned. A manual adjustment 46, such as a screw and knob may beprovided for setting the switch 40 at any desired effective temperature,by raising or lowering the block 43. The proportions of the members 40may be proportioned so that the combined action of block 43 andthermostat 4| approximates very closely the effective temperature, asnow wellknown in the air conditioning art.

V In the operation of the device shown in Fig. 1, and wheneverconditions in the space require it, switch 40 starts the operation ofthe unit I! condenser I6.

after the fan ID has been placed in operation by the closing of handswitch 40a. Air enters at 41, either from the space A or from theoutside or both, and passes in thermal exchange relationship with theevaporator I4, evaporator I5, and If the relative humidity of the spaceA is too high, as determined by the setting of the psychrometer 26, thecondenser I6 is maintained at an upper position so that heat istransferred from the air to the evaporator I4. Here substantially all,or a large part of the sensible heat of the air above its dew point isremoved. Thereafter, when the air comes under thermal exchange with theevaporator I5 moisture is condensed from the air and the air may befurther cooled. Thereafter the heat which was removed by the evaporatorI4 is restored to conditioned air by the condenser I6 in which thesecondary refrigerant condenses and from which it returns to theevaporator I4. When the relative humidity in space A is sufficientlylow, the condenser I6 is placed in the lower dotted line position by thepsychrometer 26, so that the secondary refrigerant is quickly trapped inthe condenser I6and the heat transfer from the air to the secondaryrefrigerant is stopped. Under such conditions the air is acted upon onlyby the evaporator I5 which cools the air and may also dehumidify it,thus reducing its dry bulb temperature with or without reducing its wetbulb temperature.

In the modification shown in Fig. 2, a fan III], is driven by a motorIII, forcing a stream of air through the casing II2 into the space IIJUAthrough the outlet I I3. The air comes in thermal exchange relationshipwith the secondary refrigerant evaporator II4, the primary refrigerantevaporator II4, the primary refrigerant evaporator H5, and the secondaryrefrigerant con denser HE. A refrigerant liquefying unit III is placedin primary refrigerant flow relationship with the evaporator I I5, and,as in Fig. 1, includes a compressor ||8, condenser IISl. receiver I20and motor I2I. The primary liquid refrigerant flows through the line I22to a valve I23 and returns through the evaporated refrigerant line I24to the compressor I I8. The valve I23 is provided with a'thermostaticbulb I 25. The parts thus far described may have substantially the sameconstruction and action as previously described with respect to thecorresponding parts in Fig. 1, The flow of secondary refrigerant may becontrolled in a slightly different manner, however. Thus the secondaryrefrigerant flow line I30 may be provided with valves I50 and HI. Thevalve I5I may be actuated by dry bulb I52, while the valve I 5| may beactuated by a wet bulb I53, both bulbs being placed in the space IIIOA.The refrigerant liquefying unit II'I may be controlled in accordancewith air conditions in the space IIIBA. Thus the motor I2I may becontrolled by a comfort responsive switch similar to switch 40, notshown, or, if desired, the motor I2I may be controlled by snap switchesI54 and I55 placed in parallel electrical relationship and which areoperated respectively by the wet bulb I56 and the dry bulb I 51 placedin the space IUIIA. The wet bulb I56 and switch'I54 may, however, bereplaced by the psychrometer shown in Fig. '7,

In the operation of the device shown in Fig. 2, air enters either fromthe outside or from the space IOOA, or from both, through inlet I45under the action of the fan I III. The stream of air thus created comesin thermal exchange with the evaporators H4 and I I5 and the condenserH6. If the dry bulb temperature is so high that the capacity of therefrigerant liquefying unit I ll will be taxed to the limit for coolingpurposes, then the dry bulb I52 closes the valve I50. Under suchconditions the flow of secondary refrigerant between the evaporator Hiand condenser H6 is stopped or reduced by the closure valve I50. Undersuch conditions, the entire cooling of the air is performed by theevaporator H which first reduces the temperature of the air to the dewpoint of the air and thereafter, if the liquefying unit II? hassufficient capacity, moisture is condensed from the air. However, if thedry bulb temperature is not so high, but the relative humidity issufficiently high to maintain the wet bulb temperature relatively high,then the wet bulb I53 opens the valve IM and the valve iEIi opensbecause the dry bulb temperature is not very high. Secondary refrigerantflow between evaporator I I I and condenser I I6 is then possible.

,Under such conditions the air stream first trans fers heat to thesecondary refrigerant in evaporator H 3. Thereafter it comes in thermalexchange with the evaporator IIE where moisture is removed, andthereafter the heat removed at II lis introduced into the air by thecondenser H6. Thus the air passing through the casing IIZ under suchconditions is dehydrated without lowering the dry bulb temperature toany great extent. The flow of refrigerant between evaporator El i andcondenser H6 need not be stopped completely, but may be merely modulatedby the valves I50 and I5I. The motor III is connected to the leads I16and I'll by lines I12 and In and controlled by switch II I. which mustbe closed before the automatic controls can operate motor I2 I.

Instead of governing the passage of refrigerant through the pipe I30 asshown in Fig. 2, it may be governed in accordance with relative humidityas shown in Fig. 3. Thus the valve I62, which is substituted for valvesI 50 and I5 I, may be opened and closed by the psychrometer IIiI which,conveniently, may take the form of the dry bulb I62 and wet bulb I63acting in opposed relationship on the arm IM fulcrumed at I65. The armI64 actuates the bell crank I66 which in turn actuates the stem It'l ofthe valve I60. A spring I68,'which opposes the upward action of bellcrank I56, may have its tension varied by turning the screw and knobI69, and thus the setting of the psychrometer IIII can be varied so thatit actuates the valve I60 at any desired relative humidity, to suitindividual requirements.

The refrigerant liquefying unit II'l, as shown in Fig. 2, startswhenever either dry bulb or wet bulb (or relative humidity) rises abovethe particular respective settings of the switches I56 and I55 (or theswitch of Fig. 7) and stops when both the dry bulb and wet bulbtemperatures (or relative humidity) are below the respective settings ofswitches I5d and I55 (or the switch of Fig. 7). When Fig. 2 is modifiedas shown in Fig. 3, the refrigerant liquefying unit III preferably iscontrolled by a switch similar to switch i6 placed in the enclosure WAin accordance with the effective temperature.

In the modification shown in Fig. 4, the transfer of heat to thesecondary refrigerant is governed by controlling the flow of the airthrough the apparatus. In this modification, air enters through theinlet 200, either from inside or outside, or both, the enclosure 20!.The air flows through under actionof a blower 2G2 actuated by a motor'203. The air travels either through the. passageway 204 or 205, or both,depending on the setting of the damper 20%. When the damper is in theposition illustrated in Fig. 4, a set of dampers 2W is closed so thatair flows through the passageway 2G in thermal contact only with theprimary refrigerant evaporator 208 and thence past the dampers 209through the outlet 2H] into the enclosure 2!. Under such conditions theair is subjected to the cooling effect of the evaporator 208 only.

If it is desired to remove moisture from the air without lowering thedry bulb temperature greatly, the damper 20B swings towards the leftabout the pivot 2i I, under which circumstances all or a portion of theair stream flows from the blower 200 through the passage 2% in thermalexchange with the secondary refrigerant evaporator 2I2, thence incontact with the primary refrigerant evaporator 208, thence through thewholly or partially opened dampers 201 in thermal exchange with thesecondary condenser 23 and then through the outlet 2M into the space20I. Under such conditions the air has a portion or all of its sensibleheat above its dew point transferred into the secondary refrigerant at29.2, thereafter it has moisture removed by condensation by thermalexchange with the evaporator ditioned air at 2W.

The action of the damperaand consequently the amount of heat which istransferred into secondary refrigerant may be controlled in accordancewith conditions in the space 20B. Thus a psychrometer 2I5 may operatethebell crank 2I6 which in turn operates the rods 2II and 258 whichgovern the positions of the dampers 206, 2M and 209. The psychrometer2I5 may take the form of a wet bulb m and the dry bulb are, placed inopposed relationship and tending to actuate the rod. 22I which isconnected to the bell crank 2I6. When the relative humidity is high, thepressure in the wet bulb 2I9 tends to be nearly equal to that of thebulb 220. Under such conditions the. flow through passage 265 andthrough dampers 201 is increased. When the relative humidity is low, thepressure in the dry bulb 220 tends to be much greater than in the wetbulb 2H9. Under such conditions the flow tends to be through thepassageway 2M and through the damper 209. -An adjustment 222 in the formof a screw and knob may be provided by which the tension of spring 223may be varied and thus the setting of the psychrometer 2I5 may beadjusted for any desired relative humidity. Thus the thermal exchangebetween air and the secondary refrigerant may be varied by changing thedampers 206, 2G? and 209 to fully open, fully closed or any intermediateposition.

The cooling action of the primary refrigerant in the evaporator 208 maybe varied in accordance with conditions in the air. Preferably thecontrol of such cooling action is made responsive to the conditions inthe enclosure 20 I. The operation of the refrigerant liquefying unit 22dwhich is connected to the evaporator 208, may be controlled by switches225 and 226 which are placed (or relative humidity) in the space 20|rises above the settings of the respective switches, the motor 22!operates until the temperatures of both the dry and wet bulb (or therelative humidity) are lowered below the setting of the respective Ahand switch 230 may be placed in switches. such a manner that the blower202 must first be started before the motor 22'! can be operated by theswitches 225 and 226.

The refrigerant liquefying unit 223 may include a compressor 231,primary refrigerant condenser 232, and a receiver 233 in primaryrefrigerant flow relationship. Liquid refrigerant may flow through theline 235 to the valve 235, similar in construction and operation to thevalve 23, and which is provided with a thermostatic bulb control 233similar to bulb 25. The evaporated refrigerant returns through the line233 to the compressor 231.

If, desired, the operation of the unit 224 may be made responsive toeffective temperatures.

, Under such conditions, a switch, similar to switch 40, may be placedin the space 201, and may replace switches 225 and 223 together withtheir bulb controls.

In the modification shown in Fig. 5, a slightly different form of airflow control may be used than that shown in Fig. 4. Air may enterthrough the inlet 300 from the space 301 or from outside space, or fromboth. It may flow under action of a blower 302 driven by motor 303either into the passageway 304 or passageway 305 or both. If it flowsthrough thepassageway 304 it comes into thermal exchange relationshipwith the evaporator 308 by passing through the passages 309 formed bythe corrugated metal sheet 310 which is placed inside of the metal box311 the sides of which come in contact with the coils 312 of theevaporator 308. After passing through the passageways 309, the air isdischarged through-the passageway 313, and through outlet 314, into thespace 301.

If the damper 315 swings to the left, then the air from blower 302 flowsinto passageway 305,

from whence it comes in thermal exchange with l the secondaryrefrigerant evaporator 316 thence in thermal exchange with theevaporator 308 thence in thermal exchange with the secondary refrigerantcondenser 31'1. Thereafter the air is discharged through the outlet 318into the space 301. Under such conditions the air flowing in thermalexchange with the evaporator 308 passes through vertical passageways 319formed by the corrugated metal sheet 320 placed in contact with thecoils 312 of the evaporator 308.

The flow of air throughthe apparatus, and consequently the amount ofheat which is transferred to the secondary refrigerant, is governed inaccordance with air conditions, preferably the relative humidityconditions of the air in space 301. Thus the .psychrometer 321 actuatesthe lever 322 which in turn actuates the rod 323 which is connected tothe damper 315 and switches it about the fulcrum 324. The psychrometer321 may include a dry bulb 325 and a wet bulb 326 in opposedrelationship. The construction is such that as relative humidity rises,the pressures in the bulbs 325 and 326 tend to equalize, and under suchconditions the damper M5 is swung upwardly towards the left causing theflow through passageway 305 in thermal exchange with the evaporators3l6, 300 and with the condenser 30?. When the relative humidity is low,then the. tendency of the flow of air is through the passageway 304. Aspring apogee 321 opposes slightly the thrust of dry bulb 325 and itstension may be adjusted by the screw and knob 323 so that the relativehumidity to which the psychrometer is responsive may be varied forindividual requirements.

It is to be understood that, with respect to both Figs. 4 and 5 theposition of the air dampers may be intermediate, so that part of the airmay be flowing in thermal contact with the secondary refrigerant whilepart of the air does not come in thermal contact with the secondaryrefrigerant. Thus the action described may vary from one extreme to theother and to any intermediate position.

The primary evaporator 308 may be connected to a refrigerant liquefyingunit 321.. This unit may include a motor .328, compressor 329,primaryrefrigerant condenser 330and liquid receiver 331. Liquid primaryrefrigerant flows through the line 332, through valve 333, similar tovalve 23, into a lower header 334. From thence the refrigerant 'fiows inparallel relationship through a plurality of sinuous conduits 312 to theupper header 335. From thence the evaporated refrigerant returns throughthe line 336 to the compressor 329. The valve 333 may be provided with athermostatic bulb 331 similar in construction and action to the bulb2 5.

The cooling action of theprimary refrigerant may be controlled bystarting and stopping the liquefying unit 321. Thus the motor 328 may bestarted and stopped by the switches 338 and 339 placed in electricalparallel relationship and which are actuated by dry bulb 340 and wetbulb 341 respectively, or by the phychrometer shown in Fig. 7,substantially the same as the switches 225 and 226 in Fig. 4. A handswitch 342 may be provided in such a position that the motor 303 must befirst operated before the motor 328 can be operated. If desired, theswitches 338 and 339 may be replaced by a switch similar to' switch 40in which case the operation of the unit,32| will be in response to theeffective temperature in space 301.

In Fig. 7 is shown a switch which may be made to replace the wet bulbswitches 154, 225 and 339. In this structure the wet bulb 400 opposesthe dry bulb 401 through rod 402 and acts on the snap switch 403 throughthe medium of a cam lever 406 fulcrumed at 401. The spring 404 placesits tension in opposition to the dry bulb and may be adjusted by knob405. The switch may start and stop the motor in accordance with relativehumidity in the enclosure, starting it when the relative humidity ishigh and stopping it when low.

While the preferred form of automatic controls have been specificallyillustrated and described, it is to be understood that their form andcharacter may be modified, if desired. For example, wherever a dry bulbthermostat is illustrated or described, the same may be replaced by awet bulb thermostat, humidistat or effective temperature responsiveinstrument. Likewise wherever a wet bulb thermostat, humidistat oreffective temperature responsive instrument is illustrated or described,the same may be replaced by any one of the other three controls referredto.

While the form of embodiment of the present invention as hereindisclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow.

What is claimed is as follows:

1.5m air conditioning apparatus for which an air stream is established,a secondary refrigerant evaporator in thermal exchange relationship withsaid stream, a primary refrigerant evaporator in thermal exchangerelationship with said stream, a secondary condenser connected. to saidsecondary refrigerant evaporator in secondary refrigerant flowrelationship and in thermal exchange relationship with conditioned air,a refrigerant liquefying unit connected in primary refrigerant flowrelationship with said primary refrigerant evaporator and meansresponsive to a function of the psychrometric properties of the airautomatically controlling said liquefying unit.

2. An air conditioning apparatus for which an air stream is established,a secondary refrigerant evaporator in thermal exchange relationship withsaid stream, a primary refrigerant evaporator in thermal exchangerelationship with said stream, a secondary condenser connected to saidsecondary refrigerant evaporator in secondary refrigerant flowrelationship and in thermal ex stream, a secondary condenser connectedto said secondary refrigerant evaporator in secondary refrigerant flowrelationship and in thermal exchange relationship with conditioned air,a refrigerant liquefying unit connected in primary refrigerant flowrelationship with said primary refrigerant evaporator, means responsiveto psychrometric air conditions for controlling the fiowgof. primaryrefrigerant in said primary refrigerant evaporator.

4. An air conditioning apparatus for which an air stream is established,a secondary refrigerant evaporator in thermal exchange relationship withsaid stream, a primary refrigerant evaporator in thermal exchangerelationship with said stream, a secondary condenser connected to saidsecondary refrigerant evaporator in secondary refrigerant flowrelationship and in thermal exchange relationship with conditioned air,a refrigerant liquefying unit connected in primary refrigerant flowrelationship with said primary refrigerant evaporator, means responsiveto the psychrometric conditions of the air for automatically controllingthe flow of secondary refrigerant and means responsive to psychrometricair conditions for controlling the operation of said refrigerantliquefying unit.

5. An air conditioning apparatus for which an air stream is established,a secondary refrigerant evaporator member in thermal exchange relationship with said stream, a primary refrigerant evaporator in thermalexhange relationship with said stream, a secondary condenser memberconnected to said secondary refrigerant evaporator member in secondaryrefrigerant flow relationship and in thermal exchange relationship withconditioned air, a refrigerant liquefying unit corinected in primaryrefrigerant flow relationship with said primary refrigerant evaporator,and

- sition of one of said members in accordance with psychometric airconditions whereby the effect of said members on said air stream isvaried.

'7. An air conditioning apparatus comprising means establishing an airstream, a secondary refrigerant evaporator member, a primary refrigerantevaporator and a secondary refrigerant con-denser member in said airstream, a primary refrigerant liquefying unit connected to I saidprimary refrigerant evaporator, means for varying the position of one ofsaid members in accordance with psychrometric air conditions whereby theeffect of said members on said air stream is varied and means governingthe flow of primary refrigerant in accordance with air conditions.

8. An air conditioning apparatus comprising means establishing an airstream, a secondary refrigerant evaporator, a primary refrigerantevaporator and a secondary refrigerant. condenser in said air stream,means controlling the flow of secondary refrigerant between saidsecondary refrigerant evaporator and said condenser in accordance withrelative humidity and temperature conditions, a primary refrigerantliquefying unit, and means controlling the operation of said liquefyingunit in accordance with-conditions of air.

'9. An air conditioning apparatus comprising a secondary air cooler, asecondary airwarmer, a primary air cooler, means for flowing air oversaid coolers and warmer, and means for causing air to flow at leastpartly over said secondary air cooler, primary air cooler and secondaryair warmer and at least partly over said primary air cooler alone.

10. An air conditioning apparatus comprising a secondary air cooler, asecondary air warmer, a primary air cooler, means for flowing air oversaid coolers and warmer, means for causing air to flow at least partlyover said secondary air cooler, primary air cooler. and secondary airwarmer and at least partly over said primary air cooler alone, and meansautomatically controlling the flow of air in accordance with airconditions.

11. Air conditioning apparatus comprising a casing, means causing air toflow through said casing, a secondary air cooler in'said casing,

a primary air cooler in said casing, a secondary air warmer in saidcasing, and damper means for varying the flow of air from a path oversaid secondary air cooler, primary air cooler and secondary air warmerto a path over said primary air cooler.

12. An air conditioning apparatus comprising a casing, means causing airto flow through said casing, a secondary air cooler in said casing, aprimary air cooler in said casing, a secondary air warmer in saidcasing, damper means for varying the flow of air from a path over saidsecondary air cooler, primary air cooler and secondary air warmer to apath over. said primary air cooler, and means governing said dampermeans in accordance with air conditions.

13. An air conditioning apparatus comprising a casing, means causing airto flow through said casing, a secondary air cooler in said casing, aprimary air cooler in said casing, a secondary air warmer in saidcasing, damper means for varying the flow of air from a path over saidsecondary air cooler, primary air cooler and secondary air warmer to apath over said primary air cooler, and means governing the cooling powerof said primary air cooler in accordance with air conditions.

An air conditioning apparatus comprising a casing, a blower causing airto flow in a generally upward direction through said casing, a secondaryrefrigerant evaporator in said casing, a primary air cooler in saidcasing above said evaporator, a secondary refrigerant condenser abovesaid air cooler, damper means for direct ing air mainly first past saidsecondary refrigerant evaporator or mainly first past said primary aircooler and thereafter mainly past said secondary refrigerant condenseror mainly by passing said condenser.

'15. An air conditioning apparatus comprising a secondary air cooler, aprimary air cooler, a secondary air warmer, means causing air to flowpast said air coolers and air warmer, said primary air cooler having airflow passageway means connected to receive air from said secondary aircooler and having independent air flow passageway means connected toby-pass said secondary air cooler.

16. An air conditioning apparatus comprising a secondary air cooler, aprimary air cooler, a secondary air warmer complementary to saidsecondary air cooler, means causing air to flow past said air coolersand air warmer, said primary air cooler having air-flow passageway meansconnected to discharge air past said secondary air warmer and havingindependent air flow passageway means connected to by-pass saidsecondary air warmer.

17. An air conditioning apparatus comprising a secondary air cooler, aprimary air cooler, a secondary air warmer, means causing air to flowpast said air coolers and air warmer, said primary air cooler havingair-flow passageway means connected to receive air from said secondaryair cooler and discharge said air past said secondary air warmer, andhaving independent air-flow passageway means connected to by-pass saidsecondary air cooler and said secondary air warmer.

18. An air conditioning apparatus comprising a secondary air cooler, aprimary air modifier, a secondary air warmer, said air modifier having aplurality of corrugated metal sheets in thermal contact with said airmodifier with the corrugations forming air passageways, some of saidcorrugations having a different direction from other of saidcorrugations, some of said corrugations forming air passageways betweensaid secondary air cooler and said secondary air warmer, and other ofsaid corrugations being connected to by-pass said air cooler and airwarmer.

19. An air conditioning apparatus comprising a secondary air cooler, aprimary air modifier, a secondary air warmer, said air modifier having aplurality of corrugated metal sheets in thermal contact with said airmodifier with the corrugations forming air passageways, some of saidcorrugations having a difierent direction from other of saidcorrugations, some of said corrugations forming air passageways betweensaid secondary air cooler and said secondary air warmer, and other ofsaid corrugations being connected to bypass said air cooler and airwarmer, and damper means to vary the flow of air through saidcorrugations.

20. An air conditioning apparatus comprising means ,for cooling air,fluid flow means to remove sensible heat from air about to contact saidmeans for cooling air, means to introduce said heat into conditionedair, and means for controllingthe operation of said cooling means inaccordance with eifective temperature.

21. The method of conditioning air which comprises transferring heatfrom air to a circulating fluid, cooling the air in accordance withefiective temperature conditions whereby moisture is removedindependently of said fluid, and removing said heat from said fluid.

HARRY B. HULL.

